1. Field of the Invention
The present invention relates to an instrument panel with an air bag door.
2. Description of the Related Art
FIG. 5 shows a car instrument panel P provided with an air bag door D in front of a front passenger's seat. The air bag door D is provided, on its back, with an air bag apparatus S as shown in FIG. 6. FIG. 6 is a cross-sectional view taken along a line 6--6 of FIG. 5. The air bag apparatus S consists of a folded air bag A, an igniter I, and a casing C that accommodates the air bag A and igniter I. The casing C has a top opening that is covered with the air bag door D. If the car receives a large shock due to, for example, collision, the air bag apparatus S causes the igniter I to inflate the air bag A and open the air bag door D, from behind the door D, and to expand the air bag into the car.
The instrument panel P is of a type that allows the air bag door D to bend toward a windshield and is composed of an instrument panel core 61, a foam layer 63 formed on the surface of the panel core 61, and a skin 65 disposed on the foam layer 63. In this example, the skin 65 has an easy-to-break part 66 whose shape and position correspond to those of the air bag door D and whose strength is low. When the air bag A inflates, the easy-to-break part 66 causes the foam layer 63 and skin 65 to break along the part 66, to thereby open the air bag door D as shown in FIG. 7. A reference mark T is an imaginary line along which the foam layer 63 is expected to break.
The panel core 61 is formed from, for example, hard resin into a given instrument panel back shape and has an air bag opening O, which is substantially square, at a position corresponding to the air bag door D. When the air bag A inflates, it pushes the back of the air bag door D at the opening O, opens the door D, and expands into the car. The air bag opening O is provided with an air bag door core 67. The door core 67 reinforces the back of the air bag door D, is made of a metal or synthetic resin plate having a proper thickness, and has dimensions to cover the air bag opening O. An edge of the door core 67 on a windshield side is attached to the vicinity of an edge of the air bag opening O on the windshield side with threaded members 69 such as bolts.
With this instrument panel P, an inflating air bag pushes the back of the air bag door D, and at this time, a fixed part 70 of the door core 67 collectively receives stress to deform the panel core 61 and door core 67, thereby hindering the smooth opening of the air bag door D. To solve this problem, one proposal fixes a plate-like reinforcing retainer 71 to the top of the fixed part of the door core 67, to improve the strength of the fixed part of the air bag door D. The retainer 71 is a frame having a center opening whose dimensions are substantially the same as those of the air bag opening O. The retainer 71 may be fixed to the upper periphery of the opening O so that the fixed part of the door core 67 is sandwiched between the retainer 71 and the panel core 61.
If the car is suddenly stopped or hits another car in front, the forehead of a person in the front passenger's seat may hit the instrument panel P. In this case, the retainer (frame) 71 is fixed to the panel core 61 to improve the rigidity of the panel core 61 around the air bag door D, and therefore, the panel core 61 will not break, to increase the impact on the person's head.
In the panel type that makes the air bag door D bend and open toward the windshield W as shown in FIG. 8 when the air bag inflates, the position hit by the person's head at a sudden stop substantially agrees with the fixed part 70 of the door core 67 as indicated with an arrow mark "a". In this case, the influence of the retainer (frame) 71 on the person's head is large and undesirable.